1. Field of the Invention
This invention relates to an aparatus for chamfering a notch of a semiconductor wafer, which performs the chamfering work of the notch while keeping the wafer rotating round the central axis perpendicular to the main surface thereof. More particularly, this invention relates to a chamfering apparatus which is furnished with a profiling mechanism to be operated specifically in the chamfering work.
2. Description of the Prior Art
On account of effective application of photolithography, it has been customary for wafers such as semiconductor wafers to have an orientation flat (hereinafter referred to as "OF") formed thereon by grinding off to leave a short linear cut in part of the periphery of a wafer thereby facilitating correct positioning of the wafer on an exposure device.
The formation of the OF, however, inevitably results in removal of a large portion of the wafer. Particularly in the production of wafers of a large diameter, the cumulative amount of portions wasted by this removal is so large as to impair the yield of products conspicuously. The fact that this impaired yield prevents expensive semiconductor wafers from being efficiently utilized has posed a problem.
In the circumstances, the practice of imparting a notch substantially in the shape of the letter V or substantially in the shape of an arc to the periphery of a given wafer has come to prevail for the purpose of efficiently utilizing produced wafers. Particularly the V-shaped notches have been finding extensive utility by reason of their outstanding accuracy of positioning.
Since the wafers are destined to be conveyed a number of times on production lines as in the process for manufacture of devices, their peripheries are possibly subject to chippings on colliding with parts of equipment used in the manufacturing process and the produced semiconductor devices consequently suffer from degradation of characteristic properties. It has been customary, therefore, for the wafers to have their peripheral parts chamfered.
The wafers furnished with a notch as described above, however, have found on adaptability for any work of conventional chamfering technique because the notch is small in size as compared with the peripheral length of a wafer. As the semiconductor IC's have gained in number of components per chip, however, there come to entail the drawback that the notch of their wafers causes chippings when the wafers are positioned in the process of device production by aligning the notches to a pin of rigid material. Since sharp edges of the wafers are not easily removed by machining, the sharp edges conspicuously increase occurrence of dust and the effort to preclude chipping fails. This fact has posed a problem too serious to be ignored.
This invention, initiated in the light of this problem, has as an object the provision of an apparatus for chamfering a notch of a wafer, which apparatus is capable of easily and accurately chamfering a sharp edge such as of the notch and enabling the work of chamfering the notch to be carried out in high efficiency. Moreover, this apparatus enjoys simplicity of construction.